Speedo Mystery
Thread Starter
Instructor
Joined: Jun 2000
Posts: 148
Likes: 0
From: Chatham Ontario
Speedo Mystery
I can’t explain this one and would appreciate any ideas. 1980 auto with cruise. A while back the speedo bounced around and then quit. Turns out that the cruise transducer was locked up. I get another transducer that works and get everything hooked back up. When I put the end of the cable that goes into the bullet into a drill it all works and you can run the needle to whatever speed you want. However, when I put it where it belongs inside the bullet the speedometer does not move at all. I have driven it like this all summer and today the speedo started to work again. I pulled over and got out the gps to check the accuracy and it was remarkably close for its age. It was short lived though as it stopped working again further down the road. Any ideas on what is engaging and not engaging? Why it would work some of the time? Earlier when I had the bullet all apart it seemed like the small plastic gear fit well with the end of the cable.
Melting Slicks
Joined: Feb 2018
Posts: 2,326
Likes: 721
From: Marietta GA
You need to remove the cable where it attaches to the cruse control, then jack the car up and see if the cable shaft is turning. The plastic speedometer gears are notorious for stripping as they are plastic. Also the small bracket that holes it to the transmission can be disfigured. I have a 73 with a manual transmission, the speedo quit and a Corvette shop replaced the plastic gear, it lasted about ten miles. The shop said the gear was moving inside the transmission, and they had to remove the transmission and have a guy rebuild the transmission.
